Mining and surface support.



A. LANGERFELD.

MINING AND SURFACE SUPPORT.

APPLICATION FILED MAR. 11, I913.

ARTHUR LANGERFELI), OF SCRANTON, PENNSYLVANIA.

MINING AND SURFACE SUPPORT.

Specification of Letters Patent.

Patented Dec. 5, 1916..

Application filed March 11, 1913. Serial No. 753,639.

To all whom it may concern:

Be it known that I, ARTHUR LANGERFELD,

a citizen of the United States, residing at 729 Alder street, in the city of Scranton, county of Lackawanna, State of Pennsylvania, have invented a new and useful Improvement in Mining and Surface Supports, of which the following is a specification.

This invention relates to supports in mines, and is especially useful where second mining is done, which consists in reducing or scipping pillars, or in entirely removing or robbing pillars that were left in the mines during the first mining to support the roof, or to carry the overlying or adjacent rock or earth, so as to prevent the caving in of gangways, airways, haulways, shafts, and chambers.

When second mining is done in localities where there are houses, highways, pipe lines, or other valuable structures that depend for their support on the pillars in the mines, or where there are other veins or mines above the one in which the second mining is to be done, and that would be damaged by depressions, settling, or caveins, or so distorted that they could not be mined afterward, then it becomes a question whether the value of the coal or minerals in the pillars is greater than the losses that would be caused by settling, subsidences, or cave-ins, if the pillars are removed or weakened.

In abandoned mines in which the pillars are not removed by second mining the pillars gradually become weaker and slowly yield. Wooden props rot and give away altogether. Cement or concrete cogs or supports give away entirely when the clastic limit of the cement used is exceeded by the weight or pressure on it. This also causes depressions or cave-ins.

The purpose of my invention is to supply practicable means for supporting the roof of mines, tunnels, or other cavities in the earth, and especially for supplying a substitute for pillars that are to be mined out, and for props, cogs, or pillars that have become weakened and are yielding or may yield. Such means must be cheap enough to cost less than the net value of what is gained or preserved by them, in order to be practicable or useful, and the principal feature of usefulness of my invention is that my means are so much cheaper than any others heretofore used that it will be economical or profitable to use my means in many cases where second mining would be too'costly in the old way. My means will also be beneficial to miners because they will make second mining safer; and they will be valuable to occupants of land overlying old mine workings which can not be entered for putting in supports, as is more fully explained hereinafter. The material which I use is ice, and the manner in which I fill the cavities with ice is varied to suit the conditions in each case or 10- cality.

In the accompanying drawing Figure l is a vertical section of pitching strata containing veins of coal of which 1 is mined out and filled with ice; 8 is partly mined, and has pillars 9 left in; 2 is an unmined vein. 3 is a hill; 4 is a stand pipe or hollow structure built on the shaft 5. 6 is a barrier or retaining wall. 7 is the out-crop of the ice filled worked out mine. Fig. 2 is a plan showing mine pillars 10 provided with cut waters 11, and cross cuts 12. 13 is a barrier pillar. The arrows show the flow of the ice. Fig. 3'is a vertical section of a valley A containing a coal basin. 14: is a vein of coal cropping out at 15 in the hill sides at about equal altitudes.

Where ice is plenty I take the ice into the mine and put it where it is needed, and after filling all the cavities as nearly as can be done conveniently, I also fill a shaft 5, Fig. 1, slope 3, Fig. 1 or hollow structure 4, Fig. 1 that rises as far above the filled cavities as is necessary to subject the ice to a sufficient pressure to support the roof or surroundings. This pressure will be transmitted through the ice in every direction, because ice is not a rigid solid; it is an imperfect fluid and is plastic enough to flow, although it flows only very slowly. For this reason it will gradually fill every part of the cavities in a mine. Ice also has the property of regelation or freezing together, and for that reason it will soon form a solid mass. As the specific gravity of ice is much less than that of rock, coal and earth, it would be slowly squeezed out of the mine by the pressure of overlying strata. I therefore provide a sufficient permanent pressure on the ice to counteract this difference,-by keeping the said hollow structure 4, Fig. 1 rising above the mine filled with ice up to a certain height or head. Most of the mines are near hills or mountains which make it convenient and inexpensive to .locatethe hollow structure. Openings or outcrops, 6, Fig. 1 lower down can be closed by concreteor' masonry. The upper part of the hollow structure 4L, Fig. 1 can be filledwith water to keep up the pressure -in summer, or it can be closed and filled with compressed air. If water has accumulated in the hollow structure and the water recedes into the mine, it will be necessary to freeze it. I do this either by conducting very cold air or liquid air into this water, or by sinking very cold ice into it that is weighted by stones-or other material heavier than water, so as to make this ice sink down to the other ice. By first making this ice *extra cold it willfreeze additional water and freeze together. fIt is best to use cobble stones for weighting ice for this purpose because angular stones are liable to pack and block up passages through which the iceis to flow. 7

It is of advantage'to mix as much sand, gravel, ashes, slate or other worthless solid materials that'may be at handwith the ice, because the ice will carry these materials along and will deposit'them wherever the ice may melt; Materials that decay or soften in time should be avoided for this purpose.

Ithas been found that waste materials, cnlm,'orsan d when flushed into a mine and depended upon to sustain the surface will yield up to 15% before they become packed tight enough to prevent a subsidence of the surface This will be. overcome when such loose materials are anywhere 111 a mine and a. flow Office goes in againstthem, because the pressure of the ice will pack such materials as tight as is necessary to make them unyielding.

The manner in which the cavities are filledwith ice must be varied to suit the conditions. Ifthe cavities lie in a basin or depression the ice will naturally fill them, but

if the mine pitches I first put in barrier dams 6, Fig. 1 where needed to hold the ice. In some cases these dams must be made strong enough to hold :ice pressure the same as though. the entire mine, were filled with water having as much pressure as, is necessary to, sustain the surface. Considerable expense can be saved in such cases by first building light dams, and then filling in before them with loose stones for some distance. The pressure of the ice. will jam these stones so tightly that they will add to the strength of the dam. Besides that the ice will flow in between these stones and freeze them all together.

When pillars are to be robbed or mined out. I apply my method in the following manner: InIpitc hingmines-I commence to either fill the spaces between the pillars with ice and follow this up from the lowest part as. fast as the second mining is done, or I first provide the above described hollow structure 4, Fig. 1 for supplying head or pressure, and then fill or feed in the ice from there, depending on the flow of the ice to follow the second mining ope 'ations. This flow will be similar to the flow of glaciers, but can be made faster by increasing the head, because the rate of the flow of ice depends mainly on the pressure upon it. Observations have shown that glaciers low from one to four inches per day, varying with pressure and temperature. pressure on confined ice can be made greater than the pressure on open glacier ice, and the flow of mine ice can therefore be made faster where desired. Where needed I place temporary retaining walls similar to the barrier 13, Fig. 2 to hold or divert the ice stream, and in some places I place stone or concrete pillars 10, Fig. 2 shaped like the hull of ships with their prow facing the flow of ice and provided with steel cutwaters 11, Fig. 2 to cut and divide the ice stream; otherwise the ice would push these pillars away. here necessary these pillars must be arched toward the flow and suitably let into the roof and bottom or fi-oor to hold.

In most of the mines the temperature is above the freezing point. In summer this is caused by the warm air that is drawn through the mines to ventilate them, mainly, and partly by the many lamps and explosions of powder, etc, and by steam pipes, men and mules. In winter the ventilating air is very cold for too short a time to make much difference. There is no heat produced in the mines by nature, except a small amount where air comes in contact with coal and some of its impurities. In anthracite mines this source of heat is so slight that it is negligible. The temperature in coalmines not exceeding a depth of about 600 feet generally averages 60. The temperature of the coal, mine ale and rock with which the ice will come in contact is thereforeal'so generally about (30. on the temperature of the ice whether any of it, or how much of it will melt when it comes in contact with something warmer. In practice the temperature of ice varies from 32 to. about 60 below 0.

The latent heat of water is about 142. That is: in order to freeze water having a temperature of' 32 there must be withdrawn from it about 142 British thermal units per pound. having a tempo 'ature of 32 is to be melted about 142 B. T. U. must be impartedto each pound of such ice to melt it all. The water from such melted ice will then have the same tempe 'ature of 82 as the ice had before be- But the It depends i And conversely, if ice kit ing melted. The said quantity of heat of 142 B. T. U. is required by nature to change or convert water in crystalline form, commonly called ice, to water in liquid form, without any perceptible rise in the temperature of the ice while it melts and in the melted ice or water. The quantity of heat that was imparted to the ice to make it all melt becomes what is called latent heat in the water and acts as the cause of liquidity and therefore can not and does not also act to raise the perceptible temperature or warmth.

If ice that is to be melted is colder than 32, then as much more than the said 142 B. T. U. will be required and must be imparted to such very cold ice as is required to first raise the temperature of this ice to 32. The specific heat of ice is only about onehalf that of water; that is: one pound of ice requires only about one-half as much heat, or B. T. U. per pound, to raise its temperature a certain number of degrees, as one pound of water requires for the same rise in temperature. Therefore, for instance, if ice having a temperature of -10 is to be melted, its temperature must first be raised to 32 before it will melt at all. Then if any more heat is imparted to it, it will begin to melt on its surface. To melt a pound will require about one-half of 10 plus 32, or 21 B. T. U. to raise the temperature of such cold ice to 32, and then 142 more B. T. U. will be required per pound to melt it all. The total heat, expressed in B. T. U.

in this case is therefore per pound about 21 plus 142 or 163 B. T. U.

The specific heat of coal and rock is much less than that of ice, so that it would take the heat of that much more rock or coal than ice to melt a certain quantity of ice by means of the heat or warmth in rock or coal with which the ice may come in contact. For these reasons the heat of from one to four feet depth of rock or coal would usually be required to melt one foot depth of ice.

Coal and rock are very refractory; that is: they conduct heat very poorly and very slowly. For this reason the ice that is in contact with the rock or coal will melt more slowly as the rock and coal get cooled, and when the surface of the rock and coal touching the ice is cooled down to 32 then the melting stops almost entirely. In very deep mines there is too much heat in the rocks for cheaply filling them with ice, but such deep mines do not need to be filled for surface protection.

While pillars are being removed from iced mines the air for the miners can be cooled down to 32, then the ice will not be melted by the air currents, and men can work comfortably in that temperature. But if the air is a little warmer than 32 it would not melt much of the ice, because the specific heat of air is very low, so that it would take a very large quantity of air that is only a little warmer than ice to melt any considerable part of the ice.

In some parts of the mines it may be necessary to provide vents for the air, so that it can get out and let in the ice. In most places there are fissures enough in the rock to let both air and water out. Ice will pass through such fissures so very slowly, and in such small quantities that this will not be material.

If a mine is filled with ice before any of the pillars are robbed or taken out, then the second mining may be done by driving ways through the ice from pillar to pillar and filling in the spaces of the pillars mined out with ice. Such second mining would have to be done quickly in small areas so that the ice would not get time to flow into the gangways etc.

I claim as new and useful 1. The filling of mines, tunnels, or cavities in the earth with ice, and confining it therein in such a manner that it can not flow out when any of the overlying or adjoining parts of the earth rest upon, or press against the ice.

2. The filling of mines, tunnels, or cavities in the earth with ice, confining it therein, and subjecting it to pressure.

3. The filling of mines, tunnels, or cavities in the earth with ice and subjecting the ice to pressure by means of a head.

4. The filling of mines or other similar cavities in the earth with ice, and subjecting .the ice to pressure by means of a head produced by material capable of flowing and contained in a stand pipe or equivalent hollow structure internally communicating with the ice.

5. The art of adding to an ice filling in mines and similar cavities when the uppermost level of the ice has gone down, by

adding water thereto and freezing this water by means of very cold pieces of ice weighted with material heavier than ice and sunk into the water.

6. The filling of mines, tunnels, or cavities in the earth with ice by running the ice into them by glacial flow, and providing against any outflow.

7. The safeguarding of mines and anything above or adjacent to mines by flowing ice into them, cutting the flow in front of pillars to cause it to divide and flow around the pillars and finally confining the ice under pressure.

8. The safeguarding of the surface over mines that have been partly filled with culm or other flushing materials, by filling the remaining spaces with ice and subjecting the ice to a sufficient pressure to cause it to flow and pack the mine full.

9. The art of filling mines, tunnels, or

' other cavities in the earth by flowing a mixcavities in the earth'by fiowingamixture of ice and pebbles orcobble stones into 7 them;

11. The art of second mining and providing'sui face support and roof support comprising the steps of filling the mine with 141' ice, mining out the pillars, replacing the p11- lars by ice, confining the ice and subjecting it to pressure.

ARTHUR LANGERFELD.

Witnesses:

J OI-IN P. WINOHEL, GEO. E. GRIFFITH.

Gopies'of this patent may be obtained for five cents each, by addressing the Commissioner of Patents.

' Washington,D G. 

